Method and apparatus for joining strip ends employing a stitcher assembly

ABSTRACT

A method of joining lengths of strip in which the trailing and leading ends, respectively, of successive coils of strip are clamped in overlapping relationship, subjected to a punching operation to provide a series of deformed portions along a line perpendicular to the center line of the strip, subjected to a flattening operation along said series of deformations to effect the tight interengagement of the strip ends along the deformations, and subsequently subjected to a second punching and flattening operation to form a second series of interengaging deformations a spaced distance from the first deformations, all while the strips are clamped in fixed position. The strip stitcher assembly has a fixed base on which are mounted the entry and exit clamps. A punch and die assembly and a flattener assembly are mounted on a subframe slidable on the fixed frame of the stitcher along the center line of the strip. A pair of hydraulic cylinders mounted in back-to-back relationship are employed to index the subframe of the stitcher, actuation of the first cylinder moving the subframe a distance equal to the separation between the center line of the punch and die assembly and the center line of the flattener assembly and subsequent actuation of the second cylinder moving the subassembly a further equal distance in the same direction.

United States Patent [151 3,670,398

Minton [451 June 20, 1972 [54] METHOD AND APPARATUS FOR 57 ABSTRACT JOINING STRIP ENDS EMPLOYING A A method of joining lengths of strip in which the trail d STITCHER ASSEMBLY leading ends, respectively, of successive coils of st fig 23c [72] Inventor Carl R Mimon c/o ADS Machinery clamped in overlapping relationship, subjected to a punching p- P O 1027 warren Ohio operation to provide a senes of deformed portions along a line 44482 perpendicular to the center line of the strip, subjected to a flattening operation along said series of deformations to effect [22] Filed: Feb. 13, 1970 the tight interengagement of the strip ends along the deformations, and subsequently subjected to a second punching and flattening operation to form a second series of interengaging deformations a spaced distance from the first deformations, all 52 us. C1 .29 505, 29 514, 228/3 While the Strips are clamped in fixed POSifiOII- The Strip [51] Int (1| I 2 39/00 stitcher assembly has a fixed base on which are mounted the 58 Field of Search ..228/5, 6, 6.5, 44, 3; 219/124, entry and exit P A Punch and die assembly and a 219/125. 29/429 430, 505 514 tener assembly are mounted on a subframe slidable on the fixed frame of the stitcher along the center line of the strip A [21] Appl. No;: 11,205

- pair of hydraulic cylinders mounted in back-to-back relation- [56] References Cited ship are employed to index the subframe of the stitcher, actua- UNITED STATES PATENTS tion of the first cylinder moving the subframe a distance equal to the separation between the center line of the punch and die 3,007,301 10/1961 Cooper .219/1 25 assemuy and the center line of the flatten assembly and 3,190,525 6/1965 Foley et a1. 3,198,931 8/1965 Klempay..... 3,270,180 8/1966 Morley et a1 ...2l9/81 sequent actuation of the second cylinder moving the subassembly a further equal distance in the same direction.

I 10 Claims, 11 Drawing Figures Primary Examiner-John F. Campbell Assistant Examiner-R. J. Craig Att0rr 2ey-Peter L. Klempay PATENTEDJum m2 sum 2 or 2 FIG. 9

FIG.8

' FIG. 4

FIG. 2

FIG. 3

INVENTOR. CARL H. MINTON 64; $154 FIG? AGENT FIG. 6

METHOD AND APPARATUS FOR JOINING STRIP ENDS EMPLOYING A STITCHER ASSEMBLY This application relates to a method for joining trailing and leading edges of successive lengths of strip by the formation of stitches in the overlapped strip ends, that is, by the formation of flattened deformed portions in the overlapped strips, and to apparatus for effecting the method. More particularly, the invention relates to a method for stitching metal strips and to the apparatus for effecting the same in which two parallel lines of the interlocked deformations are formed in the overlapped portions of the strip while the strip lengths are held stationary.

It is customary in the continuous processing of metal strip by, for example, annealing to provide an arrangement for joining the trailing end of one strip to the leading end of a successive coil of strip so that a continuous supply of strip may be available for use in the processing line. It is, of course, necessary to stop the tail end of strip being processed while the joining operation is accomplished and while loopers or accumulators may be provided in the processing line to provide a continuous supply of strip to the processing equipment while the joining operation is being accomplished, it is imperative that the joining operation be accomplished in a minimum of time. Among the methods employed to join the successive coils of strip is that of stitching, that is, the formation of a series of interlocking deformations across the width of the overlapped ends of the strip. In order to achieve an adequate interlocking of the successive strip lengths it is preferable to form two spaced rows of stitches in the overlapped strip ends. Heretofor, this has been accomplished by first punching a series of deformations into the overlapped strips, jogging the strips forward to bring the deformations into line with a pair of flattening platens, forming a second row of defonnations, and again jogging the strip forward to bring the second row of deformations in line with the platens. The jogging of the strips however, is undesirable as it introduces transient stresses into the strip length passing through the processing equipment which may distort the strip or effect its proper tracking through the processing equipment. It is preferrable if the strip lengthsare stopped at the beginning of the joining operations and are not moved again until the entire joining operation has been completed. In addition to introducing undesired transient stresses into the subsequent strip length, the jogging of the strip may produce defective joints between the overlapped strips, especially where light gauge strip is being processed. When the strip is jogged forward after the formation of a single row of stitches, the stitches are subjected to high stress and, where thin materials are involved, the stitches are unable to carry the full stress. As a result, the first row of stitches is torn. In extreme cases, the destruction of the first .row of stitches may be so extensive that all the stresses between the trailing and leading strip ends are carried by the second row of stitches. Should the second row of stitches be subjected to high stresses at a later point in the processing line, the strips will separate necessitating the costly and time-consuming rethreading of the line.

It is the primary object of the present invention to provide a method for securing the overlapped ends of successive strip lengths by the formation of parallel rows of stitches which can be accomplished without the necessity of jogging the strip lengths forward. In accordance with the principles of the present invention this objective is accomplished by providing a stitcher assembly in which the punch and die portions and the flattening platens may be indexed along the path of travel of the strip to bring the punch and die assembly and the flattening platens into alignment with successive spaced regions of the strip without the necessity for moving the strip.

It is also an object of the present invention to provide a method and apparatus for stitching together the overlapped ends of successive coils of metal strip which is capable of rapid operation. This objective is accomplished, in part, by providing a reliable and simple indexing mechanism for the punch and die and flattening assemblies of the stitcher which is capable of indexing these assemblies to their desired positions without the need for any further adjustments or alignments.

Another object of the present invention is the provision of a method and apparatus for stitching successive lengths of metal strip to one another which produces stitches of consistently uniform quality. This objective is accomplished by the provision of an indexing arrangement which accomplishes positive indexing of the punching and flattening assemblies so that the flattening assembly is always brought into exact alignment with the previously formed deformations.

A further object of the invention is the provision of a method and apparatus for joining overlapped strip ends with spaced rows of stitches in which all the rows of stitches are equally stressed. This is accomplished in the present invention by preforming all of the joining operations while the strip ends are held stationary, eliminating the overstressing of any of the rows of stitches which occurs when the strip must be advanced to permit formation of additional rows of stitches.

The above and other objects and advantages of the invention will become apparent upon consideration of the following specification and the accompanying drawings wherein there is shown a preferred embodiment of the invention.

In the drawing:

FIG. 1 is a schematic elevational view of a continuous strip annealing line;

FIG. 2 is a side elevational view of the strip stitcher assembly of the present invention;

FIG. 3 is an end elevational view of the strip stitcher assembly;

FIG. 4 is a plan view of the strip stitcher assembly;

FIG. 5 is a vertical sectional view taken along the line VV of FIG. 3;

FIGS. 6 and 7 are highly schamatic views similar to that of FIG. 5 but on a reduced scal and showing the punching and flattening mechanisms of the stitcher assembly in their second and third operating positions, respectively;

FIG. 8 is a fragmentary vertical section taken along the line VlII-VIII of FIG. 2 and showing the strip guides at the entry end of the stitcher assembly;

FIG. 9 is a fragmentary vertical section taken along the line IX-IX of FIG. 2 and showing the strip clamps of the entry side of the stitcher assembly;

FIG. 10 is a fragmentary vertical section taken along the line XX of FIG. 2 and showing the punch and die components of the stitcher assembly; and

FIG. 11 is a fragmentary vertical section taken along the line XI-XI of FIG. 10.

A typical strip annealing line 10 is illustrated in FIG. I. In such an annealing line a metal strip 11 supplied from a coil 12 to a series of processing apparatus, including, in sequence, cleaning and drying equipment 13, a first accumulator 14, an annealing furnace l5, pickling equipment 16, a second accumulator l7, and shearing and recoiling equipment 18 and 19. In order to assure a continuous supply of strip to the processing line a second uncoiler 20 is also provided and, when the supply of strip from the uncoiler 12 becomes exhausted, the leading end of the coil of the strip on the uncoiler 20 is sheared by the shear 21 to provide a straight end for the strip and is then overlapped with the trailing end of the previous coil of strip and joined thereto by the stitcher 22. During this operation the supply of strip in the accumulator 14 is used to supply a continuous length of strip to the annealing furnace 15. In order to reduce the number of times that the strip length must be started and stopped to accomplish the stitching operation, I provide stitcher apparatus which is capable of making two parallel rows of stitches in the overlapped strip ends while the strip is held in a fixed position.

DESCRIPTION OF A PREFERRED EMBODIMENT The stitcher assembly employed in the annealing line of FIG. 1 has a rectangular base 24. Mounted on the base 24 are entry and exit strip side guides 26 and 28, respectively, entry and exit strip clamps 30 and 32, respectively, and a punching and flattening mechanism 34 for forming stitches in the overlapped strip ends.

The strip edge guides of the entry end of the stitcher are illustrated in FIG. 8. The edge guide assemblies consist of a pair of L-shaped guides 36, 38 which are free to slide in a horizontal direction at right angles to the path of travel of the strip along ways 40. One of the guides 36 is connected to the upper reach of an endless chain 42 while the other guide 38 is connected to the lower reach of the chain 42. Also connected to the chain 42 is the operating rod of a hydraulic cylinder 44. This arrangement causes the guides 36 and 38 to move equal distances toward or away from the centerline of the path of travel of the strip when the hydraulic cylinder 44 is actuated. Since the guides 36 and 38 are always at an equal distance from the centerline of the desired path of travel of the strip, these guides will direct incoming strip so that its centerline coincides with the centerline of the path of travel. The exit guides 28 are of identical construction.

The entry strip clamps 30, illustrated in FIG. 9, are of conventional construction, consisting of a lower fixed platen 46 and a movable upper platen 48 which is controlled by a pair of air cylinders 50. The exit strip clamp 32 is similarly constructed.

The stitcher mechanism 34 is mounted on a frame 52 which is slideably supported in ways 54 mounted on the upper surface of the base 24, allowing the frame 52 to be moved horizontally and parallel to the path of travel of the strip. The frame 52 is composed of a pair of vertical side members 56 joined by lower and upper crossmembers 58 and 60, respectively. The side and crossmembers thus define a large rectangular opening 62 through which is passed the strip lengths. A ram 64 having ways 66 slideable on the side members 56 is carried within the opening 62 and is moved by means of a hydraulic cylinder 68 mounted on the upper crossmember 60.

A die set is supported by the upper surface of the crossmember 58 beneath the ram 64. This die set has bed plates 72 and 74 which are held in vertical alignment by columns 70 mounted on the bed plate 72 and extending through the upper bed plate 74. Carrier plates 76 and 78 are mounted on the facing surfaces of the upper and lower base plates 72 and 74. Mounted on the lower carrier plate 76 are a series of punches 80 and die and stripper plates 84. The upper carrier plate 78 is likewise provided with a series of punch elements 82 and a die and stripper plate 86. As will be seen from FIG. 10, the punches 80 and 82 are mounted in staggered relationship to one another along a line perpendicular to the centerline of the path of travel of the strip. This arrangement results in the formation of a series of deformations across the width of the strip, the defonnations extending alternately upwardly and downwardly across the strip.

The frame 52 also carried a flattener mechanism consisting of a fixed lower platen 88 and a movable upper platen 90 slideably carried on the side members 56 and operated by a hydraulic cylinder 92.

The frame 52 has a downwardly and laterally projecting portion 94 at its lower end. This projecting portion 94 is connected at its lower end to the free end of the piston 96 of a hydraulic cylinder 98. Mounted in back-to-back relationship with the hydraulic cylinder 98 is a second hydraulic cylinder 100, the free end of whose piston 102 is connected to a bracket 104 secured to the base 24. Each of the cylinders 98 and 100 is of the double acting type and has a stroke exactly equal to the distance between the centerline of the punch and die assembly and the centerline of the flattening platens 88, 90. The cylinders 98 and 100 are supported by a roller 106 running on a rail 108 which is secured to the base 24.

Mounted on the base 24 adjacent the exit clamp 32 is a horizontal plate 110 which projects inwardly toward the frame 52. The upper surface of this plate 110 is provided with a plurality of strips 112 extending in spaced parallel relationship to one another and to the centerline of the strip path of travel. Mounted on the upper surface of the lower crossmember 58 of the frame 52 are a plurality of strips 114 which project outwardly toward the exit side of the apparatus in spaced parallel relationship to one another and to the centerline of the strip path of travel. When the subframe 52 is at its leftmost position, the outer ends of the strip 114 are supported by the plate 110 and, as the frame 52 is moved toward the right, the strips 1 l4 slide along the plate 1 10 in the spaces between the strips 1 12. The strips 112 and 114 serve to provide a support for the trailing or leading end of a strip length and prevent such an end from dropping into the opening between the frame 52 and the exit end of the base 24.

OPERATION OF THE STRIP STITCHER During running of the strip, the entry and exit clamps 30 and 32 are open, the ram 64 is in its uppermost position, and the movable platen of the flattener is also in its upper position, permitting the unimpeded passage of strip through the stitcher. The hydraulic cylinders 98 and are both at their fully extended positions, thus positioning the frame 62 with its associated punching and flattening mechanisms at its leftmost position, adjacent the entry side of the stitcher.

When the supply of strip from the first coil 12 is exhausted, the strip 11 is stopped with its trailing end at the stitcher 22. The leading end of the second coil of strip 20 is then threaded into the stitcher 22, the side guides 26 and 28 serving to align the leading and trailing strip ends so that their centerlines are coincident with one another and with the centerline of the strip pass line. The strip ends are now clamped by the entry and exit clamps 30 and 32. The cylinder 68 is now actuated to move the ram 64 downwardly causing the punch and die assembly to form a series of deformations across the width of the overlapped strips, the deformations projecting alternately above and below the strips. Upon completion of the punching operation the ram 64 is retracted causing the die set to open. A rod is now inserted through the deformations, the downwardly extending deformations passing below the rod while the upwardly projecting defonnations pass above the rod. One of the hydraulic cylinders 98, 100 is now actuated to pull the frame 52 toward the right. As explained above, the stroke of each of the cylinders 98 and 100 is exactly equal to the distance between the centerline of the punch and die assembly and the centerline of the platens of the flattener assembly. Thus, upon actuation of one of these cylinders the frame 52 is moved to the right so that the defonnations in the overlapped strips are now aligned with the platens 88 and 90. The cylinder 92 is now actuated to move the platen 90 downwardly against the overlapped strips to tightly lock the rod within the deformations. The platen 90 is then withdrawn upwardly. In addition to moving the frame 52 so that the flattener platens 88, 90 are aligned with the previously formed deformations, the actuation of one of the cylinders 98, 100 has also advanced the punch and die assembly along the strip lengths. The cylinder 68 is again actuated forcing the ram 64 downwardly to form a second line of deformations across the width of the overlapped strips. This second line of deformations is spaced from the previously formed line of deformations a distance equal to the distance between the centerline of the centerline of the punch and die assembly and that of the flattener platens 88, 90 and, consequently, equal to the stroke of each of the hydraulic cylinders 98, 100. After the ram 64 has been withdrawn to its upper position and a rod inserted through the deformations, the other of the hydraulic cylinders 98, 100 is actuated to again move the frame 52 toward the right, the frame being moved a distance equal to the separation between the centerline of the punch and die assembly and that of the flattener platens. The flattener is again actuated, completing the second row of stitches.

On completion of the second flattening operation the flattener platen 90 is withdrawn upwardly and the entry and exit clamps 30, 32 are released. The strip lengths have now been stitched together and are again moved through the stitcher to replenish the strip supply in the accumulator l4 and to supply strip to the subsequent processing equipment. The hydraulic cylinders 98 and 100 are again actuated to extend both of these cylinders, moving the frame 52 back to its initial position adjacent the entry side of the frame 24, preparatory to the stitching of the subsequent coil of strip.

It should be understood that changes may be made in and to the preferred embodiment of the invention described above. Other types of strip guides and of entry and exit clamps may be employed. While the frame indexing arrangement has been described with specific reference to a stitcher assembly, it will be apparent that the use of the indexing arrangement is not so limited. Rather, the arrangement may also be used advantageously with any type of strip joining equipment which has spaced apart operating stations or which performs successive operations at spaced intervals along the strip length. Likewise, other arrangements for advancing the frame 52 may be substituted for the back-to-back hydraulic cylinder arrangement shown. However, it should be noted that the illustrated arrangement provided an economic and reliable indexing means for the frame and the associated punching and flattener assemblies and that this arrangement assures the accurate indexing of the frame. While specific reference has been made to the forming of a pair of spaced rows of stitches across the overlapped strip lengths and while such a double row of stitches is preferrable to insure a reliable joint between the successive strip lengths, the stitcher assembly may be employed to form a single row of stitches, if desired, by omitting the second punching operation, the second indexing of the frame, and the second flattening operation.

Although no control circuitry has been illustrated or described herein, it will be readily apparent to one skilled in the an that suitable controls may be provided to effect the manual or automatic operation of the stitcher assembly. Thus, once the strip ends have been overlapped and aligned with one another and with the centerline of the path of travel of the strip, the stitching operation may be readily accomplished en-- tirely under automatic control, thus permitting the most rapid and accurate joining of the successive strip lengths. The inherently positive indexing accomplished by the back-to-back arrangement of the hydraulic cylinders 98 and 100 eliminate the need for providing elaborate sensing circuitry to assure the proper positioning of the punch and flattener assemblies.

It should now be apparent that there has been provided a novel arrangement for joining the trailing and leading ends, respectively, of successive strip lengths which fulfills the objectives set out above. By providing an assembly in which the strip lengths are held stationary during the entire stitching operation, the present invention substantially reduces the transient stresses imparted to the strip length passing through the subsequent processing equipment by eliminating the need to jog the strip lengths over short distances between successive stages of the stitching operation. Further, by providing an arrangement in which the punching and flattening assemblies may be rapidly and accurately indexed to successive operating positions, the present invention reduces the time required to join successive strip lengths and assures a high degree of uniformity of the joints in the overlapped strip ends. By holding the strip ends in a fixed position during the successive formation of multiple rows of stitches, the possibility of defective stitches occurring due to over-stressing of a single row of stitches while jogging the strip is eliminated.

While only the best known embodiment of the invention has been illustrated and described in detail herein, the invention is not limited thereto or thereby. Reference should therefore be had to the appended claims in determining the true scope of the invention.

I claim:

1. The method of joining the trailing and leading ends respectively, of successive strip lengths, comprising the steps of:

placing the end portions of said successive strip lengths in overlapping relationship;

clamping said overlapped portions at two spaced intervals to hold the strips in fixed position;

determining, at a first station intermediate said overlapped portions, discrete areas of the strip extending transversely across the overlapped portions;

advancing said first deforming station along said strip lengths while holding the strip lengths stationary to bring said first deforming station into alignment with an undeformed area of said overlapped portions and to bring a second deforming station into alignment with said deformed areas of said overlapped portions;

further deforming, at said second station, said deformed areas to form interlocking deformations in said overlapped portions;

unclamping said overlapped portions; and

returning said first and second stations to their initial positions.

2. The method according to claim 1 further including: the intermediate steps, prior to the unclamping of said overlapped portions, of deforming, at said first station, a second series of discrete areas extending transversely across said overlapped portions; further advancing said first and second deforming stations along said strip lengths to bring said second deforming station into alignment with said second series of deformed areas of said overlapped portions; and further deforming, at said second station, said second series of deformed areas to form an interlocking deformation in said overlapped portions. V

3. The method according to claim 2 further including: the intermediate step, prior to the clamping of said overlapped portions, of aligning said successive strip lengths so that the centerlines thereof are colinear with one another and are colinear with the centerline of the desired path of travel.

4. Apparatus for joining the trailing and leading ends, respectively, of successive strip lengths, comprising:

a base;

entry and exit strip clamps mounted on opposite ends of said base;

a frame slideably mounted on said base between said entry and exit clamps;

a first operating station mounted on said frame and adapted to perform a first strip joining function in the overlapped portions of said strip lengths;

a second operating station also mounted on said frame and adapted to perform a second function at the region of said overlapped strips in which said joining function was performed; and

indexing means for moving said frame longitudinally relative to the strip lengths while holding the strip lengths stationary so as to bring said second operating station into alignment with the region of said overlapped strip lengths in which said joining function was performed.

5. Apparatus according to claim 4 wherein said indexing means includes means for moving said frame to a third position, the separation between the second and third positions of said frame being equal to the separation between the first and second positions thereof.

6. Apparatus according to claim 5 wherein the distance between the first and second positions of said frame and between the second and third positions of said frame is exactly equal to the distance between the centerline of said first operating station and the centerline of said second operating station.

7. Apparatus according to claim 6 wherein said indexing means comprises a pair of hydraulic cylinders, the stroke of each of said cylinders being equal to the distance between said first and second operating stations, the operative end of one of said cylinders being connected to said frame, the operative end of the other of said cylinders being connected to said base, and said cylinders being connected to one another in back-toback relationship.

8. Apparatus according to claim 7 further including: strip guiding means as the entry and exit sides of said base, said guiding means serving to align said leading and trailing strip ends so that the centerlines thereof are colinear with one another and are colinear with the centerlineof the strip path of travel.

9. Apparatus according to claim 4 wherein said first operating station includes: a plurality of lower punch elements mounted in spaced, linear relationship on a fixed plate carried by said frame, a plurality of upper punch elements mounted in spaced, linear relationship on a plate vertically slideable on said frame, said upper and lower punch elements lying in the same vertical plane but offset from one another so as to form a series of alternately upwardly and downwardly projecting deformations across the width of said overlapped strip lengths.

10. A strip stitching assembly for securing the overlapped trailing and leading ends, respectively, of successive strip lengths, comprising: a base; a frame supported by said base and slideable thereon in the direction of the strip pass line; a fixed bed plate mounted on said frame; a vertically moveable bed plate carried by said frame and vertically aligned with said fixed bed plate; punch and die elements carried by said fixed and moveable bed plates and arranged to form a series of spaced deformations extending transversely of the centerline of said overlapped strip ends; means to raise and lower said moveable bed plate; a fixed platen mounted on said frame, spaced from said fixed bed plate and having its principal axis transverse to the centerline of said overlapped strip ends; a vertically moveable platen carried by said frame in vertical alignment with said fixed platen; means to raise and lower said moveable platen; and a pair of hydraulic cylinders, the operative end of one of said cylinders being connected to said frame, the operative end of the other of said cylinders being connected to said base, said cylinders being connected to one another in end-to-end relationship, and the stroke of each of said cylinders being equal to the distance between the centerline of said fixed bed plate and the principal axis of said fixed platen, the arrangement being such that actuation of one of said cylinders moves said frame from an initial position along the strip pass line to a position wherein said platens are aligned with the deformations formed by said punch and die elements and subsequent actuation of the other of said cylinders moves said frame a further equal distance in the same direction.

F I i 

1. The method of joining the trailing and leading ends respectively, of successive strip lengths, comprising the steps of: placing the end portions of said successive strip lengths in overlapping relationship; clamping said overlapped portions at two spaced intervals to hold the strips in fixed position; determining, at a first station intermediate said overlapped portions, discrete areas of the strip extending transversely across the overlapped portions; advancing said first deforming station along said strip lengths while holding the strip lengths stationary to bring said first deforming station into alignment with an undeformed area of said overlapped portions and to bring a second deforming station into alignment with said deformed areas of said overlapped portions; further deforming, at said second station, said deformed areas to form interlocking deformations in said overlapped portions; unclamping said overlapped portions; and returning said first and second stations to their initial positions.
 2. The method according to claim 1 further including: the intermediate steps, prior to the unclamping of said overlapped portions, of deforming, at said first station, a second series of discrete areas extending transversely across said overlapped portions; further advancing said first and second deforming stations along said strip lengths to bring said second deforming station into alignment with said second series of deformed areas of said overlapped portions; and further deforming, at said second station, said second series of deformed areas to form an interlocking deformation in said overlapped portions.
 3. The method according to claim 2 further including: the intermediate step, prior to the clamping of said overlapped portions, of aligning said successive strip lengths so that the centerlines thereof are colinear with one another and are colinear with the centerline of the desired path of travel.
 4. Apparatus for joining the trailing and leading ends, respectively, of successive strip lengths, comprising: a base; entry and exit strip clamps mounted on opposite ends of said base; a frame slideably mounted on said base between said entry and exit clamps; a first operating station mounted on said frame and adapted to perform a first strip joining function in the overlapped portions of said strip lengths; a second operating station also mounted on said frame and adapted to perform a second function at the region of said overlapped strips in which said joining function was performed; and indexing means for moving said frame longitudinally relative to the strip lengths while holding the strip lengths stationary so as to bring said second operating station into alignment with the region of said overlapped strip lengths in which said joining function was performed.
 5. Apparatus according to claim 4 wherein said indexing means includes means for moving said frame to a third position, the separation between the second and third positions of said frame being equal to the separation between the first and second positions thereof.
 6. Apparatus according to claim 5 wherein the distance between the first and second positions of said frame and between the second and third positions of said frame is exactly equal to the distance between the centerline of said first operating station and the centerline of said second operating station.
 7. Apparatus according to claim 6 wherein said indexing means comprises a pair of hydraulic cylinders, the stroke of each of said cylinders being equal to the distance between said first and second operating stations, the operative end of one of said cylinders being connected to said frame, the operative end of the other of said cylinders being connected to said base, and said cylinders being connected to one another in back-to-back relationship.
 8. Apparatus according to claim 7 further including: strip guiding means as the entry and exit sides of said base, said guiding means serving to align said leading and trailing strip ends so that the centerlines thereof are colinear with one another and are colinear with the centerline of the strip path of travel.
 9. Apparatus according to claim 4 wherein said first operating station includes: a plurality of lower punch elements mounted in spaced, linear relationship on a fixed plate carried by said frame, a plurality of upper punch elements mounted in spaced, linear relationship on a plate vertically slideable on said frame, said upper and lower punch elements lying in the same vertical plane but offset from one another so as to form a series of alternately upwardly and downwardly projecting deformations across the width of said overlapped strip lengths.
 10. A strip stitching assembly for securing the overlapped trailing and leading ends, respectively, of successive strip lengths, comprising: a base; a frame supported by said base and slideable thereon in the direction of the strip pass line; a fixed bed plate mounted on said frame; a vertically moveable bed plate carried by said frame and vertically aligned with said fixed bed plate; punch and die elements carried by said fixed and moveable bed plates and arranged to form a series of spaced deformations extending transversely of the centerline of said overlapped strip ends; means to raise and lower said moveaBle bed plate; a fixed platen mounted on said frame, spaced from said fixed bed plate and having its principal axis transverse to the centerline of said overlapped strip ends; a vertically moveable platen carried by said frame in vertical alignment with said fixed platen; means to raise and lower said moveable platen; and a pair of hydraulic cylinders, the operative end of one of said cylinders being connected to said frame, the operative end of the other of said cylinders being connected to said base, said cylinders being connected to one another in end-to-end relationship, and the stroke of each of said cylinders being equal to the distance between the centerline of said fixed bed plate and the principal axis of said fixed platen, the arrangement being such that actuation of one of said cylinders moves said frame from an initial position along the strip pass line to a position wherein said platens are aligned with the deformations formed by said punch and die elements and subsequent actuation of the other of said cylinders moves said frame a further equal distance in the same direction. 